1. Technical Field
The present disclosure relates to surgical fastener applying apparatus. More particularly, the present disclosure relates to surgical fastener applying apparatus that include surgical fasteners that are configured to apply varying compressive forces in tissue.
2. Background of the Related Art
Many varieties of surgical fastener applying apparatus are known in the art, some of which are specifically adapted for use in various surgical procedures including, but not limited to, end-to-end anastomosis, circular end-to-end anastomosis, open gastrointestinal anastomosis, endoscopic gastrointestinal anastomosis, and transverse anastomosis. Suitable examples of apparatus which may be used during the course of these procedures can be seen in U.S. Pat. Nos. 5,915,616; 6,202,914; 5,865,361; and 5,964,394.
In general, a surgical fastener applying apparatus will include an anvil that is approximated relative to a surgical fastener cartridge during use or a fastener cartridge that is approximated relative to an anvil. The anvil includes depressions that are aligned with, and/or are in registration with slots defined in the surgical fastener cartridge, through which the fasteners will emerge. To effectuate formation, the fasteners emerge from the surgical fastener cartridge and are driven against the anvil. The surgical fastener cartridge typically has one or more rows of fasteners disposed laterally outward of a channel or knife slot that is configured to accommodate a knife, or other such cutting element, such that tissue can be simultaneously severed and joined together. Depending upon the particular surgical fastener applying apparatus, the rows of fasteners may be arranged in a linear, non-linear, e.g. circular, semi-circular, arcuate, or other configuration.
Various types of surgical fasteners are well known in the art including, but not limited to, unitary fasteners and two-part fasteners. Unitary fasteners generally include a pair of legs that are adapted to penetrate tissue and connected by a backspan from which they extend. In use, subsequent to formation, certain types of unitary fasteners have a “B” shaped configuration. Typically, the two-part fastener includes legs that are barbed and connected by a backspan. The legs are engaged and locked into a separate retainer piece that is usually located in the anvil. In use, the two-part fastener is pressed into the tissue so that the barbs penetrate the tissue and emerge from the other side where they are then locked into the retainer piece.
During each of the aformentioned surgical procedures, the tissue is initially gripped or clamped between the cartridge and anvil such that individual fasteners can be ejected from the cartridge, through the slots, and forced through the gripped tissue. Thereafter, the fasteners are formed by driving them into the depressions formed on the anvil.
A common concern in each of the procedures mentioned above is hemostasis, or the rate at which bleeding of the target tissue is stopped. It is commonly known that by increasing the amount of pressure applied to a wound, the flow of blood can be limited, thereby decreasing the time necessary to achieve hemostasis. To this end, conventional surgical fastener applying apparatus generally apply two or more rows of fasteners about the cut-line to compress the surrounding tissue in an effort to stop any bleeding and to join the cut tissue together. Each of the fasteners will generally apply a compressive force to the tissue sufficient to effectuate hemostasis. However, applying too much pressure can result in a needless reduction in blood flow to the tissue surrounding the cut-line, resulting in an elevated level of necrosis, a slower rate of healing, and/or a greater recovery period.
Consequently, it would be advantageous to provide a surgical fastener applying apparatus capable of limiting the flow of blood in the tissue immediately adjacent the cut-line to effectuate hemostasis and wound closure, while maximizing blood flow in the surrounding tissue to facilitate healing.
Additionally, when tissue is clamped and compressed between the anvil and the surgical fastener cartridge, some of the fluid of the tissue is squeezed out so the tissue is compressed further at the center portions of the cartridge and anvil than at the lateral edges, thereby leaving thicker tissue at the edges. It would therefore be advantageous to provide surgical fasteners which could better accommodate these resulting different tissue thicknesses.